a) Field of the Invention
This invention relates to a rotor supportable at a side surface thereof by a needle bearing.
b) Description of the Related Art
FIG. 12 onwards show the construction of a conventional rotor. In these drawings, the conventional rotor is illustrated by way of example as being used as a bush for a one-way clutch (hereinafter simply called xe2x80x9cbushxe2x80x9d) upon bringing the one-way clutch into contact at a side surface thereof with a needle bearing. FIG. 12 is a front view of the bush, and FIG. 13 is an axial fragmentary cross-sectional view of the bush. The bush, which is designated at numeral 21, has a bearing face 27 to be brought into contact with a needle bearing 10. The bearing face 27 is provided with oil grooves 22, and oilways 24 are axially bored in the respective oil grooves 22. The bush 21 is also provided at an outer periphery thereof with indentations 28 to be fitted with an outer ring (not shown) of the one-way clutch.
Designated at numerals 10, 11 and 32 are the needle bearing, needles, and a race of the needle bearing, respectively, and load from a stator of a torque converter is borne by these needle bearings.
FIG. 14 is a diagram showing a conventional positional relationship between the oil grooves 22 in the bearing face 27 and the needles 11. As is appreciated from the drawing, the needles 11 and the oil groove 22 are completely overlapping in an area indicated by a circle A.
Keeping in step with a move toward high-powered engines, the load produced from the stator of the torque converter has increased, leading to an increase in the load borne by the bearing face 27. This has also led to an increase in the load transmitted from the needles 11 to the bearing face 27 via the race 32. Because the needles 11 completely overlap the grooves 22 as mentioned above, the race 32 yields and caves into the oil grooves 22 under the load from the needles 11. As greater contact pressures occur between the caved portions of the race 32 and the needles 11, a problem arises in that the needles 11 may eventually undergo flaking after repeatedly passing over the caved portions. To avoid this caving, it has heretofore been needed to assure the rigidity of the race by making it thicker or applying heat treatment to it.
An object of the present invention is to prevent a race of a needle bearing from yielding and caving into oil grooves of a rotor maintained in contact with the needle bearing and also to achieve reductions in the thickness, weight and manufacturing cost of the race, both, without making the race thicker or applying heat treatment or the like to the race.
In one aspect of the present invention, there is thus provided a rotor supportable at a side surface thereof by a needle bearing, said side face including a bearing face with lubricating oil grooves formed therein and being to be brought into contact with the needle bearing upon assembly, wherein the oil grooves are arranged in a positional relation ship with needles of the needle bearing such that the oil grooves and the needles of the needle bearing do not completely overlap each other along an entire circumference in a direction of rotation.
Owing to the above-described construction, the rotor according to the present invention can prevent a race of the needle bearing from yielding and caving into the oil grooves formed in the bearing face under load from the needles, can make the race smaller in thickness and lighter in weight, and can achieve a cost cut.